HCV has recently been recognized as one of the causative agents of NANB hepatitis (Non-A, Non-B). It can be distinguished from other forms of viral-associated liver diseases, including that caused by known hepatitis viruses, i.e., hepatitis A virus (HAV), hepatitis B virus (HBV), and delta hepatitis virus (HDV), as well as the hepatitis induced by cytomegalovirus (CMV) or Epstein-Barr virus (EBV). Non-A, Non-B Hepatitis was first identified in transfused individuals. Transmission from man to chimpanzee and serial passage in chimpanzees provided evidence that Non-A, Non-B Hepatitis is due to a transmissible infectious agent or agents.
Epidemiologic evidence is suggestive that three types of Non-A, Non-B Hepatitis exist: the water-borne epidemic type; the blood or needle associated type; and the sporadically occurring (community acquired) type. However, the number of agents which may be the causative of Non-A, Non-B Hepatitis is still unknown.
Clinical diagnosis and identification of Non-A, Non-B Hepatitis has been accomplished primarily by exclusion of other viral markers. Among the methods used to detect putative Non-A, Non-B Hepatitis antigens and antibodies are agar-gel diffusion, counter-immunoelectrophoresis, immuno-fluorescence microscopy, immune electron microscopy, radioimmunoassay, and enzyme-linked immunosorbent assay. However, none of these assays has proved to be sufficiently sensitive, specific, and reproducible to be used as a diagnostic test for Non-A, Non-B Hepatitis. Recently serologic tests for HCV infection have been developed and are commercially available. However, for the development of a specific and sensitive method to enable a reliable diagnosis to be made in various phases of the infection, it is of great importance that HCV can be detected instead of the detection of antibodies directed against HCV as is carried out by the present commercially available tests.
It is self-evident that an early diagnosis of a putative patient infected with HCV will be of prime importance since as a consequence treatment of the patient suffering from the disease can start as early as possible.